This invention relates to the protection of water hydrants from undesirable backpressure backflow, and back siphonage backflow. Hoses and equipment are frequently connected to freezeless outdoor water hydrants to accomplish various tasks. Significant backpressure or siphonage can be encountered during some tasks, particularly if a break occurs in the primary water line.
Freezeless wall faucets or hydrants are known in the art. Generally, these devices include a hollow housing having an interior inlet and connected to a source of pressurized water and an exterior outlet. A valve is included within the housing and is connected by means of a rod to a manually operable handle outside the housing. Rotation of the handle causes the valve to open and close. Freezeless faucets are normally wall-mounted on the exterior of a building with the valve extending inwardly with respect to the building to a point where the valve is protected from freezing by warmth from the interior of the building. The handle and outlet are located on the exterior of the building.
A freezeless water faucet with a removable valve cartridge is shown in U.S. Pat. No. 4,821,762 to Breneman. The removable valve cartridge is supported on an operating rod which extends centrally within a bore in the elongated housing of the faucet. Various methods have been tried in conjunction with such faucets to control the flow and backpressure within to prevent damage and contamination. Unfortunately, face sealing backflow preventors like the one shown by Breneman adversely affect the output flow characteristics of the faucet and require a separate spring and seat for proper sealing. In freezeless faucets, it is difficult to accommodate backpressure preventors within the housing without interfering with the operation of the centrally located valve cartridge.
Therefore, a principal object of this invention is to provide an improved backpressure and back siphonage preventor for a freezeless hydrant.
A further object of the present invention is to provide a backflow and back siphonage preventor which is mounted to the operating rod and seals against the wall of the hollow housing when the fluid forces are greater downstream than upstream of the preventor.
A further object of the present invention is to provide a backflow and back siphonage preventor which allows water to be delivered from the source so long as the valve is open and the fluid forces are greater upstream than downstream of the preventor.
A further object of the present invention is to provide a backflow and back siphonage preventor which is durable, readily serviceable, inexpensive to manufacture, and capable of self-flushing for removal of debris during operation.
A further object of this invention is to prevent failure of the backflow preventor, and particularly the sealing element forming a part thereof, under conditions of high fluid pressure.